$7.5$ liters of a certain solution contain $37$ grams of salt. What is the density of salt in the solution? Round your answer, if necessary, to the nearest tenth.
Explanation: This is a density word problem. To solve it, we can use the following equation, which is the volume definition of density: ${\text{Density}}=\dfrac{{\text{Total quantity}}}{{\text{Volume}}}$ What do we know? The ${\text{volume}}$ of the solution is ${7.5}$ liters. There are ${37}$ grams of salt in the solution, which is the ${\text{total quantity}}$. What do we need to find? The ${\text{density}}$ of salt in the solution. We can plug ${\text{total quantity}=37}$, and ${\text{volume}=7.5}$ in the equation. $\begin{aligned} {\text{Density}}&=\dfrac{{\text{Total quantity}}}{{\text{Volume}}} \\\\ &=\dfrac{{37}}{{7.5}} \\\\ &\approx 4.9 \end{aligned}$ The density of salt in the solution is approximately $4.9$ grams per liter.